Research

PhD Dissertation

The Asymmetric Nature of Time: Accounting for the Fixity of the Past and the Openness of the Future

A basic intuition we have regarding the nature of time is that there is a difference between the future and the past: the former appears to be open and the latter appears to be fixed (or closed). This intuition manifests itself in various ways. First, whereas we think of the future as partially unsettled (e.g. it is settled that I will die someday, but it is unsettled whether the first astronaut to go to Mars will be a woman), we think of the past as fully settled (e.g. it is settled that Napoleon lost in Waterloo, that dinosaurs are extinct animals). Secondly, whereas we think that there are things we can do to affect how the future will unfold (e.g. making a significant donation to an NGO, acting in an environmentally responsible manner), we think that there are not things we can do to affect how the past unfolded (“what is done is done”). Thirdly, and perhaps more radically, whereas we may only wonder how the past unfolded (e.g. “what happened to John Kennedy?”), we may wonder whether the future will unfold (e.g. “will reality continue beyond tonight?”).

The intuition of an asymmetry in openness between the future and the past is so deeply ingrained in our manifest image of the world that it seems hopeless to do without. We decide, we create, we remember, we regret. All these common attitudes – and there are many more – presuppose an open future and a fixed past. For example, when it comes to forming beliefs about what we remember or regret, we explore our mental life, i.e. we consult our memory and records, since these latter attitudes are epistemically constrained by the information we may collect about what happened to us. By contrast, when we want to know what we will decide or create, i.e. when we try to predict the outcomes of such pending processes, we do not gather psychological evidence or records, since any information we might obtain will be overridden by the processes themselves. We rather let these processes run their courses; they are almost guaranteed to produce true beliefs. This suggests that whereas our attitudes towards the past depend on the traces it left on our mental life, the future partially depends (either directly, or in an attenuated manner) on our decisions and our creations. It therefore seems that, unlike the past, the future cannot be regarded as more fixed than the processes in which we are currently engaged.

However, the main models of the temporal structure of the world do not reflect any asymmetry between the future and the past. According to eternalism and presentism, the future and the past are ontologically on a par. Eternalists hold that both the future and the past exist, while presentists hold that neither the future nor the past exists. In other words, the two main competing models of the temporal structure of the world do not ontologically distinguish the future from the past (either both of them exist or none of them exists). Therefore, neither eternalism nor presentism seems able to account for our basic intuition regarding the nature of time. Of course, one might claim that the asymmetry between the future and the past is not ontological and, therefore, that it must be accommodated otherwise than through a model of the temporal structure of the world. Nonetheless, in my PhD dissertation, I aim to demonstrate why we should reject this suggestion and opt for an alternative model – the growing block theory – that provides an ontological ground for this temporal asymmetry.

This project might be criticized for taking too seriously the asymmetry in openness between the future and the past. After all, many arguments taken from science, especially from contemporary physics, have been put forward to show that the asymmetry is in fact illusory. For example, the Theory of Relativity seems to imply the so-called block universe view, on which the asymmetry does not arise. According to this view, the block universe extends from the Big Bang to the end of time if there is one, or indefinitely, if there is not. It represents all times as equal parts of reality, i.e. without making any fundamental asymmetric distinction between them. Just as spatial places (e.g. Greenwich Village, Plaça de Catalunya) exist, despite not being here (in Switzerland), so too past and future times exist, despite not being now (in 2018). In other words, the spatio-temporal model favored by contemporary physics does not seem to reflect any difference between space and time that somehow accounts for the fact that there is no here-there space-asymmetry in the same way as there is a past-future time asymmetry. Therefore, since I take the asymmetry between the open future and the fixed past to be a robust notion, I aim to conceptually improve the way we (as non-physicists) think about the nature of time to make it compatible with the most salient scientific theories.